Thoratec Limited v AIS GMBH Aachen Innovative Solutions

21 November 2016

Mr Justice Arnold gave a decision on 28 October in the case between Thoratec Limited v AIS GMBH Aachen Innovative Solutions relating to patents concerned with ventricular assist devices. There was no dispute as to the applicable legal principles but there were some practical points to be taken from the decision.

First, there was overlap between the evidence given by the two experts for the defendant. The Order for Directions did not specify the fields of expertise for the two experts the parties were each permitted to call evidence from. As a result, the parties could call experts in any field they chose and the defendant chose experts with overlapping expertise. Mr Justice Arnold reminds parties in his decision of the well-established practice of the Patent Court not to allow duplicative evidence.

The second practical point on expert evidence is that one of the experts admitted under cross-examination that he had not written a particular sentence in his report, but that the party 's lawyers had written it and that he did not understand it. Mr Justice Arnold could not place any weight on the opinions expressed in that expert 's report. This is a useful reminder that experts should be primarily responsible for their own evidence, and that cross-examination remains an invaluable tool to discover the full facts of a matter.